Employment Law Update - August 2025

It is 25 years since the implementation of the Part-Time Workers (Prevention of Less Favourable Treatment) Regulations in July 2000. In this month’s bulletin, we focus on recent and important cases in this area, as well as a recent case on a TUPE transfer when a business changed its supplier of temporary labour.

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Part-time status must be the “sole reason” for less favourable treatment

There have been two recent cases in this area.

In Mireku v London Underground Ltd the EAT were asked to resolve the debate as to whether a claim for less favourable treatment under the Regulations requires part-time status to be the sole cause of the treatment or just had to be the “effective cause”.

Mr Mireku worked in a job-share arrangement with a colleague. Each worked two weeks on and two weeks off to cover a full-time role.

It was common practice for employees to be asked to volunteer to work overtime and Mr Mireku volunteered to work overtime during one of his “off” weeks. His offer was declined on the basis that he could not work during his 2-week off period. This decision was later changed to saying that he could volunteer to work on the overtime rota, but he would not be paid the overtime rate or receive any additional leave, because he was under the full-time threshold. Following a period of sickness, Mr Mireku moved from the Paddington Area to Whitechapel. His costs remained part of the Paddington budget though. His manager at Paddington therefore indicated that if he requested overtime, Mr Mireku should be allocated only one such shift per week without further authorisation by his Paddington manager.  

Mr Mireku brought a number of claims for being subject to a detriment, including arguing that full-timers did not need to have their requests to work overtime authorised by two managers (in his case the Paddington and the Whitechapel manager).

Mr Mireku’s claim succeeded in relation to the initial rejection of his application for overtime on the basis that he could not work in his off-weeks. However, in respect of his complaints about being denied the opportunity to work overtime at Whitechapel, the Tribunal dismissed these claims on the basis that those hours were declined for a number of reasons:

• A general desire to limit overtime post-COVID
• That Mr Mireku fell under the budget of a different manager
• The desire to make sure there was a fair opportunity to access overtime for Mr Mireku and his colleagues

Mr Mireku appealed on the basis that there was conflicting EAT case law on whether the test should be one of “sole cause” or “effective cause”. He noted that in the recent case of Augustine v Data Cars Ltd, the EAT had analysed the authorities and found that it was bound by precedent to follow the “sole cause” test, even though its own view was that the “effective cause” test seemed the better interpretation of the Regulations.

The EAT dismissed Mr Mireku’s appeal and followed the EAT’s decision in Augustine v Data Cars Ltd. It confirmed that the current test is that for it to be unlawful, the individual’s status as a part-timer must be the sole cause of the treatment. In any event, the EAT found that even had it applied the “effective cause” test, Mr Mireku’s claims would still not have succeeded as there were a number of factors that resulted in him not being granted overtime at Whitechapel, so his part-time status could not even be described as the effective cause.

Shortly after the Mireku decision, the Court of Appeal gave its judgement in the appeal of Augustine v Data Cars Ltd. Mr Augustine was a part-time driver, but had to pay the same flat £148 weekly circuit fee as full-timers for access to the company’s booking system. He argued that he should pay a pro-rata fee. His case was dismissed on the basis that the £148 fee was not charged solely because he was a part-time worker. It was because it was standard practice in the industry, not because he worked fewer hours.

This judgement was similar to the Mireku judgement. Whilst the majority (but not all) of the judges considered that, were they starting from scratch, the correct test would be one of “effective cause”, the fact was that a Scottish Court of Session decision had established that the test should be one of “sole cause” and it would not be appropriate for the Court of Appeal to overrule that. It did grant permission to appeal to the Supreme Court, who would not be bound by precedent of previous decisions and could take a fresh look at the issue. It remains to be seen what the Supreme Court decides.  

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TUPE transfer applied to change of temporary work agency

In Mach Recruitment Ltd v Oliveira the EAT were asked to consider the application of TUPE to a change in temporary work supplier.

The Claimant was initially employed by G-Staff Ltd and supplied by that agency to Butchers Pet Care Ltd (BCP). BCP later engaged a new work agency (Mach Recruitment) to provide workers and the Claimant was employed by Mach Recruitment and provided by them to BCP.

The Claimant claimed that her employment had transferred under TUPE from G-Staff to Mach Recruitment because there had been a service provision change. For there to be a TUPE transfer by way of service provision, there had to be:

• “an organised grouping of employees situated in Great Britain which has as its principal purpose the carrying out of the activities concerned on behalf of the client”.

In this case, the Claimant’s evidence was that her work during the relevant period was always with BCP, was always in the same role and she worked alongside the same people throughout. Mach Recruitment, however, argued that:

• There should only be deemed to be an “organised grouping of employees” where there is an element of deliberate planning or intent;
• The number of workers provided by the agency fluctuated, depending on BCP’s requirements, so there was no stable “organised grouping”

The EAT upheld the Tribunal Judge’s decision that there was an “organised grouping of employees”, saying that, based on the evidence before the Tribunal, it was a decision open to it. Whilst a different judge might have come to a different view, the EAT found that the decision was not perverse and would not be overturned. The Tribunal also noted that “the Respondent might have called evidence from which it could be inferred that there was no organised grouping, but it did not”. The Tribunal therefore based its judgement largely on the Claimant’s evidence.

This decision is a reminder of the wide range of circumstances of supplier changes to which TUPE might apply.